Electron emission devices include display devices wherein electrons are emitted from cathode emitter tips toward phosphor molecules (the phosphor molecules can also be referred to herein as simply "phosphor"). An exemplary display device is a Field Emission Display (FED) device, such as the prior art FED device 10 described with reference to FIG. 1.
Device 10 comprises a baseplate assembly 12 and a faceplate assembly 14. Baseplate assembly 12 includes a substrate 16. Substrate 16 is preferably formed of an insulative glass material, and can be referred to as a baseplate. Column interconnects 18 are patterned over substrate 16. Column interconnects 18 comprise a conductive material, such as, for example, a metal. In preferred applications, column interconnects comprise an assembly of three sub-layers, with the sub-layers being an aluminum layer elevationally between a pair of chromium layers.
A buffer layer 19 is formed over column interconnects 18, and a resistor layer 20 is formed over buffer layer 19. Buffer layer 19 comprises amorphous or microcrystalline silicon, and resistor layer 20 comprises conductively-doped amorphous silicon (preferably, boron-doped amorphous silicon).
Electron emission tips 22 are formed over substrate 16 at sites from which electrons are to be emitted, and can be constructed from conductively doped silicon (the silicon can be in, for example, either an amorphous or polycrystalline form). Emission tips 22 can have a number of pointed geometries, including, for example, pyramids and cones.
An extraction grid 24 (also referred to as a gate) is formed proximate emitter tips 22, and separated from substrate 16 with a dielectric layer 26. Extraction grid 24 comprises a conductive material, such as, for example, conductively doped polysilicon. Extraction grid 24 is patterned to have openings 28 extending therethrough to expose electron emission tips 22. Dielectric layer 26 electrically insulates extraction grid 24 from electron emission tips 22, and the associated column interconnects 18.
Faceplate assembly 14 of FED device 10 is provided in a spaced relation relative to baseplate assembly 12, and is held in such spaced relation by insulative spacers 38.
Faceplate assembly 14 comprises a transparent substrate 36, and a transparent anode 34 formed proximate substrate 36. Substrate 36 can be referred to as a faceplate. Anode 34 can comprise, for example, indium tin oxide, and substrate 36 can comprise, for example, glass.
Faceplate assembly 14 comprises phosphor 32 supported by substrate 36 and defining pixels. Phosphor 32 comprises a luminescent material that generates visible light upon being excited by electrons emitted from electron emission tips 22. Phosphor 32 can comprise, for example, red/green/blue phosphor triads.
A voltage source 30 is provided to generate an operating voltage differential between electron emission tips 22, grid structure 24, and anode 34. One or more of emitter tips 22 can then be electrically stimulated to cause electrons 40 to be emitted toward phosphor 32. The impact of electrons 40 with phosphor 32 causes luminescence of phosphor 32. A person looking through transparent substrate 36 can see such luminescence. Accordingly, electron emission from emitter tips 22 is converted to an image visible through faceplate assembly 16.
Clarity, or resolution, of a field emission display is a function of a number of factors, including emitter tip uniformity and sharpness. Accordingly, numerous methods have been proposed for fabrication of very sharp emitter tips (i.e., emitter tips having tip radii of 100 nanometers or less), uniformly spaced across an array. Fabrication of very sharp and appropriately spaced tips has, however, proved difficult. In light of these difficulties, it would be desirable to develop alternative methods of forming emitter tips.